Vacuum control assembly

ABSTRACT

A vacuum control assembly for operating the breaker plate of an automotive type ignition distributor through an operating rod to provide ignition spark vacuum advance for an associated internal combustion engine. A range bracket member having an elongated slot of a length determined by the desired range of degrees of ignition spark advance is rigidly secured to the assembly mounting bracket in a location at which the slot accommodates the end portion of the operating rod which engages the distributor breaker plate and is so positioned that one end wall of the slot engages the operating end portion at the point at which the operating end portion is located with engine vacuum of a magnitude at which ignition spark vacuum advance is to be initiated.

Julian et a1.

[ Dec. 9, 1975 VACUUM CONTROL ASSEMBLY [75] Inventors: Clarence L.Julian, Daleville; Robert E. Young, Anderson, both of Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: May3, 1973 21 Appl. No.: 356,724

[44] Published under the Trial Voluntary Protest Program on January 28,1975 as document no.

[52] US. Cl. 123/117 A; 123/1465 A [51] Int. Cl. F021 5/04 [58] Field ofSearch 123/117 A, 146.5 A; 92/13, 92/13.2, 99, 100

Primary ExaminerManuel A. Antonakas Assistant ExaminerW. Rutledge, Jr.Attorney, Agent, or Firm-Richard G. Stahr [5 7] ABSTRACT A vacuumcontrol assembly for operating the breaker plate of an automotive typeignition distributor through an operating rod to provide ignition sparkvacuum advance for an associated internal combustion engine. A rangebracket member having an elongated slot of a length determined by thedesired range of degrees of ignition spark advance is rigidly secured tothe assembly mounting bracket in a location at which the slotaccommodates the end portion of the operating rod which engages thedistributor breaker plate and is so positioned that one end wall of theslot engages the operating end portion at the point at which theoperating end portion is located with engine vacuum of a magnitude atwhich ignition spark vacuum advance is to be initiated.

1 Claim, 2 Drawing Figures VACUUM CONTROL ASSEMBLY This invention isdirected to a vacuum control assembly for operating the breaker plate ofan automotive type ignition distributor through an operating rod toprovide ignition spark vacuum advance for an associated internalcombustion engine and, more specifically, to a vacuum control assemblyof this type having a range bracket member which positions the operatingrod at the location at which it should be located with engine vacuum ofa magnitude at which ignition spark vacuum advance is to be initiated.

As is well known in the automotive art, the breaker plate of anautomotive type ignition distributor is operated by a vacuum controlassembly which is usually mounted upon or close to the ignitiondistributor. The vacuum control assembly includes a diaphragm which iscoupled to the breaker plate of the ignition distributor through anoperating rod having an elongated portion secured to the diaphragm andan operating end portion extending substantially normal to the elongatedportion for operatively engaging the breaker plate. Therefore, thevacuum control assembly changes the angular position of the breakerplate in response to a change of engine vacuum to which one side of thediaphragm is exposed. The diaphragm forms a seal at one side of a vacuumchamber which is in communication with the intake manifold of theassociated internal combustion engine and the vacuum chamberaccommodates a compression spring which opposes the pressure of ambientair against the exposed opposite side of the diaphragm. When manifoldvacuum increases, the pressure of ambient air flexes the diaphragmagainst the bias of the compression spring and transmits motion to thebreaker plate through the operating rod which is thereby revolved in adirection to produce ignition spark vacuum advance. With most, if notall, internal combustion engines, the ignition spark vacuum advance isto be initiated at a specific engine vacuum. However, due tomanufacturing tolerances and the resulting differences in length of theoperating rod between the several units, the point at which ignitionspark advance is to be inititiated may vary within the range of plus orminus one inch of mercury or plus or minus 3 of crankshaft rotation. Ithas been found that it is much more desirable to initiate spark vacuumadvance at the precise magnitude of engine vacuum at which ignitionspark advance should be initiated.

It is, therefore, an object of this invention to provide an improvedvacuum control assembly for operating the breaker plate of an automotivetype ignition distributor.

It is an additional object of this invention to provide an improvedvacuum control assembly for operating the breaker plate of an automotivetype ignition distrib' utor wherein a range bracket member is sopositioned that the operating rod which operates the breaker plate ismaintained at the specific location at which it is to be located withengine vacuum of a magnitude at which ignition spark vacuum advance isto be initiated.

In accordance with this invention, a vacuum control assembly foroperating the breaker plate of an automotive type ignition distributoris provided wherein a range bracket member is so positioned that theoperating rod which revolves the ignition distributor breaker plate isprecisely located at the point at which it is to be located with enginevacuum of a magnitude at which ignition spark vacuum advance is to beinitiated.

For a better understanding of the present invention, together withadditional objects, advantages and features thereof, reference is madeto the following description and accompanying drawing in which:

FIG. 1 is a top view of a vacuum control assembly of this invention, and

FIG. 2 is a sectional view of FIG. 1 taken along line 22 and looking inthe direction of the arrows.

Referring to the drawing, the vacuum control assem' bly of thisinvention includes a casing consisting of a chamber member 11 and acover member 14, a diaphragm 12 enclosed within casing 10 and acompression spring 15 interposed between diaphragm 12 and casing 10 forurging diaphragm 12 in a first direction toward the left as looking atthe drawing. Diaphragm 12 is hermetically sealed to chamber member 11 ofcasing 10 about the periphery thereof to provide a vacuum chamber 16. Avacuum port 18 is in communication with the inside of casing member 10.The side of diaphragm 12 opposite compression spring 15 is exposed toatmosphere, as is well known in the art. An operating rod having anelongated portion 20 secured to the diaphragm member 12 as at 21 and anoperating end por tion 22 extending substantially normal to theelongated portion 20 for operatively engaging the breaker plate isoscillated linearly by diaphragm member 12. A mounting bracket 25 isrigidly secured to the cover member 14 of casing member 10 and extendsin a direction along operating rod 20 for mounting the vacuum controlassembly upon or near the ignition distributor in a position at whichthe operating end portion 22 operatively engages the distributor breakerplate.

A range bracket member having an elongated slot 31 of a lengthdetermined by the desired range of degrees of ignition spark vacuumadvance from zero to maximum is rigidly secured to mounting bracket 25in a location at which slot 31 accommodates the operating end portion 22of the operating rod and is so positioned that one end wall 31a of slot31 engages the operating end portion 22 at the point at which theoperating end portion 22 is located with engine vacuum of a magnitude atwhich ignition spark vacuum advance is to be initiated.

During the manufacturing process, vacuum port 18 is exposed to aconstant vacuum of a magnitude equal to the magnitude of engine vacuumat which ignition spark vacuum advance is to be initiated in theassociated engine with which the vacuum control assembly is to be used,for example 4" of mercury. This vacuum is maintained until the rangebracket member 30 is rigidly secured to mounting bracket 25, as by spotwelds 34 and 35 for example, at a location at which end wall 31a of slot31 thereof is in engagement with the operating end portion 22.Consequently, when vacuum is removed from port 18 and the unit assumesits relaxed position, the operating end portion 22 of the operating rodis precisely located for every one of the vacuum control assemblies atthe point at which it should be located with engine vacuum of amagnitude at which ignition spark vacuum advance is to be initiated.

With most internal combustion engines, there is a predetermined maximumnumber of degrees of ignition spark vacuum advance required.Consequently, slot 31 of range bracket member 30 is designed to be of alength which will provide ignition spark vacuum ad vance only between 0and the maximum number of degrees. When the operating end portion 22 ofthe operating rod engages end wall 31b of slot 31, no more ignitionspark vacuum advance is provided.

While a preferred embodiment of the present invention has been shown anddescribed, it will be obvious to those skilled in the art that variousmodifications and substitutions may be made without departing from thespirit of the invention which is to be limited only within the scope ofthe appended claims.

What is claimed is:

l. A vacuum control assembly for operating the breaker plate of anautomotive type ignition distributor to provide ignition spark vacuumadvance for an associated internal combustion engine comprising, avacuum unit including at least a casing, a diaphragm enclosed withinsaid casing in such a manner as to provide a vacuum chamber, a springinterposed between said diaphragm and said casing for urging saiddiaphragm in a first direction, a vacuum port communicating with saidvacuum chamber and an operating rod oscillated 1 4 linearly by saiddiaphragm having an elongated portion secured to said diaphragm and anoperating end portion extending substantially normal to said elongatedportion for operatively engaging said breaker plate, a mounting bracketrigidly secured to said casing and extending in a direction along saidoperating rod, and a range bracket member having an elongated slot of alength determined by the desired range of degrees of ignition sparkvacuum advance from zero to maximum which accommodates said operatingend portion of said operating rod, said range bracket member, with apredetermined vacuum applied to said vacuum port, being positioned withone end wall thereof in engagement with said operating end portion ofsaid operating rod and rigidly secured to said mounting bracket memberwhereby an initial compression is set in said spring.

1. A vacuum control assembly for operating the breaker plate of anautomotive type ignition distributor to provide ignition spark vacuumadvance for an associated internal combustion engine comprising, avacuum unit including at least a casing, a diaphragm enclosed withinsaid casing in such a manner as to provide a vacuum chamber, a springinterposed between said diaphragm and said casing for urging saiddiaphragm in a first direction, a vacuum port communicating with saidvacuum chamber and an operating rod oscillated linearly by saiddiaphragm having an elongated portion secured to said diaphragm and anoperating end portion extending substantially normal to said elongatedportion for operatively engaging said breaker plate, a mounting bracketrigidly secured to said casing and extending in a direction along saidoperating rod, and a range bracket member having an elongated slot of alength determined by the desired range of degrees of ignition sparkvacuum advance from zero to maximum which accommodates said operatingend portion of said operating rod, said range bracket member, with apredetermined vacuum applied to said vacuum port, being positioned withone end wall thereof in engagement with said operating end portion ofsaid operating rod and rigidly secured to said mounting bracket memberwhereby an initial compression is set in said spring.